Postretirement Benefits - Schedule of Net Benefit (Details) - USD ($) $ in Millions	3 Months Ended
	Jan. 31, 2020	Jan. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plan, Cost	$ 8
Employer contributions	30	$ 131
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	2	2
Interest on obligations	21	32
Amortization of cumulative loss	25	24
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	0	142
Premiums on pension insurance	3	1
Expected return on assets	(36)	(38)
Net postretirement benefits expense	15	163
Health and Life Insurance Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1
Interest on obligations	7	12
Amortization of cumulative loss	0	0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	0	0
Premiums on pension insurance	0	0
Expected return on assets	(5)	(5)
Net postretirement benefits expense	$ 3	$ 8